分离式拼缝混凝土叠合板受力性能研究

为研究采用马镫钢筋作为抗剪拉结钢筋的分离式拼缝混凝土叠合板的受力性能,通过3块简支板的静力加载试验,对其在不同马镫钢筋布置下的荷载-挠度曲线、承载能力、变形性能进行了研究,并分析了其裂缝成因、拼缝处受力机理,推导了其开裂荷载的计算式。结果表明:规范分离式拼缝叠合板的荷载-挠度曲线发展趋势为三折线形,其开裂荷载计算与普通叠合板计算有所区别; 试件拼缝处易产生沿着叠合面的撕裂破坏,其附加钢筋容易发生局部滑移或者锚固失效; 试件屈服荷载受附加钢筋的黏结滑移影响有一定的降低,其极限承载力取决于拼缝处现浇混凝土与预制板的拉结强度; 试件拼缝处裂缝数目与宽度和马镫钢筋有关,合理改变马镫钢筋布置能够有效减少裂缝数目及宽度; 试件屈服前变形呈现整体弯曲,屈服后变形主要集中在拼缝处,最终试件均出现了混凝土压碎现象,其破坏形态呈现二折线形; 根据相关规范,针对附加钢筋滑移问题可通过锚固弯钩、加长钢筋长度、抬高钢筋位置等措施进行改进。

Mechanical Property Study on Split Joint Concrete Composite Slab

In order to study the mechanical properties of split joint reinforced concrete composite slab with stirrup as shear tie reinforcement, the load-deflection curve, bearing capacity and deformation performance of three simply supported slabs under different stirrup arrangements were studied. The causes of the cracks, the mechanical mechanism of the joints and the calculation formula of the cracking load were also analyzed. The results show that the development trend of load-deflection curve of standard split joint composite slab is trilinear, and the calculation of cracking load is different from that of common composite slab. The joint of the specimen is prone to tear along the composite plane, and the additional reinforcement is easy to slip or anchor failure. The yield load of the specimen is affected by the bond slip of the additional reinforcement, and its ultimate bearing capacity depends on the tensile strength between the cast-in-place concrete and the precast slab at the joint. The number and width of cracks are related to stirrup bars. Reasonable arrangement of stirrup bars can effectively reduce the number and width of cracks. Before yielding, the deformation of specimens present overall bending, and after yielding, the deformation is mainly concentrated in the joint. The concrete crushing phenomenon appears in all specimens, and the failure mode is close to two fold linear. According to the relevant codes, the problem of additional reinforcement sliding can be improved by anchoring hooks, lengthening the length and raising the position of reinforcement.